Safety boundary
Use equation cards, simulations, and supplied energy data only. No combustion or reactive demonstrations are required.
Explicit chemistry instruction
Two pathways can share the same net ΔH while having different activation barriers.
Catalysts change pathway and activation energy but not the reactant/product enthalpy difference.
Energy diagrams should label reactants, products, transition barriers, and ΔH separately.
Vocabulary: pathway; activation energy; catalyst; reaction coordinate; ΔH.
Worked example
A catalyzed and uncatalyzed pathway both drop 40 kJ overall, but the catalyzed peak is lower.
Guided question
Why doesn't a catalyst change ΔH?
Independent work
- Annotate two energy diagrams.
- Compare barriers and net energy change.
- Explain one catalyst effect.
Misconception check
A lower activation barrier is not the same as a more negative ΔH.
Formative check
What quantity does a catalyst primarily alter?
Reveal response
Activation energy/pathway, not net ΔH.
Mentor evidence conference
Ask Archaemenes to audit signs, pathway logic, units, and model limits.
Teacher guidance
Foundation: Label diagrams.
Core: Compare pathway models.
Extended: Relate kinetics and thermodynamics without conflating them.